A company wants to ensure that all credentials for various systems are saved within a central database so that users only have to login once for access to all
systems. Which of the following would accomplish this?

A.
Multi-factor authentication

B.
Smart card access

C.
Same Sign-On

D.
Single Sign-On

Explanation:
Single sign-on means that once a user (or other subject) is authenticated into a realm, re- authentication is not required for access to resources on any realm entity.
Single sign-on is able to internally translate and store credentials for the various mechanisms, from the credential used for original authentication.
Incorrect Answers:
A: Multifactor authentication requires a user to provide two or more authentication factors for authentication purposes. It does not guarantee that users only have to
login once for access to all systems.
B: Smart cards are credit-card-sized IDs, badges, or security passes with an embedded integrated circuit chip that can include data regarding the authorized
bearer. This data can then be used for identification and/or authentication purposes. It does not guarantee that users only have to login once for access to all
systems.
C: Same Sign-On means that users will have to re-enter their credentials, but they can use the exact same credentials they use to sign on locally.

Stewart, James Michael, CompTIA Security+ Review Guide, Sybex, Indianapolis, 2014, pp 282, 284.
http://blogs.technet.com/b/jeff_stokes/archive/2013/07/08/today-s-cloud-tip-same-sign-on-vs- single-sign-on.aspx